A tuberculosis vaccine in use for 90 years may help reverse Type 1 diabetes and eliminate the lifelong need for insulin injections, say Harvard University researchers raising money to conduct large, human studies.

Patients with Type 1 diabetes must inject insulin daily to control their blood sugar because their bodies don't produce the hormone, the result of an errant immune system that destroys insulin-producing cells in the pancreas. The vaccine, called bacillus Calmette-Guérin, or BCG, stimulated production of a protein that killed the insulin-attacking cells, according to the findings of an early-stage study published Wednesday in the journal PLoS One.

Insulin injections help control Type 1 diabetes for the 3 million Americans with the disease, though there is no cure for the condition usually diagnosed in childhood. Results of the trial showed that two of the three patients given BCG had signs of renewed insulin production. The researchers now plan a larger study that could yield results in three to five years.

The vaccine, a weakened form of the tuberculosis bacteria, stimulates production of TNF, a cell-signaling protein that plays a role in cell death. With more TNF, the body can attack those harmful immune cells while leaving the rest of the body's defenses intact. The vaccine is approved by the Food and Drug Administration for tuberculosis, though it isn't generally recommended for use in the United States. The vaccine also is approved to fight bladder cancer.